This is a counterpart application of a Japanese patent applications 2000-102619, filed on Apr. 4, 2000, 2000-251885, filed on Aug. 23, 2000, and 2000-342661, filed on Oct. 3, 2000, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a multi-electron-beam exposure apparatus, a multi-axis electron lens, a fabrication method of the multi-axis electron lens and a fabrication method of a semiconductor device.
2. Description of the Related Art
Conventionally, it is known an electron-beam exposure apparatus capable of exposing a wafer with a plurality of electron beams in order to form a semi-conductor device. For example, an electrons-beam exposure apparatus including an electron lens having a pair of magnetic plates placed in parallel relationship with each other is disclosed in U.S. Pat. No. 3,715,580 or in U.S. Pat. No. 4,209,702. The pair of magnetic plates has a plurality of through holes at places corresponding to each other for respectively having the plurality of electron beams pass therethrough in order for focusing images.
The conventional electron beam exposure apparatus disclosed in above patents corrects the focus of the electron beams by using exciting coils provided between the pair of magnetic plates. However, it is difficult to provide the exciting coils between the pair of magnetic plate. Especially, in case that the electron beam exposure apparatus uses a number of electron beams, it is difficult to provide them between the pair of magnetic plate.
Therefore, it is an object of the present invention to provide a multi-beam exposure apparatus using a multi-axis electron lens, a fabrication method of a multi-axis electron lens and a fabrication method of a semiconductor device, which is capable of overcoming the above drawbacks accompanying the conventional art. The above and other objects can be achieved by combinations described in the independent claims. The dependent claims define further advantageous and exemplary combinations of the present invention.
According to the first aspect of the present invention, an electron beam exposure apparatus for exposing a wafer, comprising: a multi-axis electron lens operable to converge a plurality of electron beams independently of each other; and a lens-intensity adjuster including a substrate provided to be substantially parallel to said multi-axis electron lens, and a lens-intensity adjusting unit operable to adjust the lens intensity of said multi-axis electron lens applied to said electron beams passing through said lens openings, respectively.
The multi-axis electron lens may include a plurality of magnetic conductive members arranged to be substantially parallel to each other, said plurality of magnetic conductive members having a plurality of lens openings forming a plurality of lens openings allowing said plurality of electron beams to pass therethrough, respectively.
The lens-intensity adjusting unit may include an adjusting electrode provided to surround said electron beams from said substrate to said lens opening, said adjusting electrode being insulated from said plurality of magnetic conductive members.
A length of said adjusting electrode in a direction in which said electron beams are radiated may be longer than an inner diameter of said adjusting electrode.
The adjusting electrode may be provided to project from one of said magnetic conductive members other than a magnetic conductive member opposed to said substrate.
The lens-intensity adjusting unit may include a plurality of adjusting electrodes provided to surround said electron beams, respectively, from said substrate to said lens openings.
The lens-intensity adjusting unit may include a means operable to apply different voltages to said plurality of adjusting electrodes.
The lens-intensity adjusting unit may include an adjusting coil operable to adjust magnetic field intensities in said lens openings, said adjusting coil being provided to surround said electron beams from said substrate along a direction in which said electron beams are radiated.
The adjusting coil may be arranged to be insulated from said magnetic conductive members.
The lens-intensity adjusting unit may further include: a plurality of adjusting coils provided to surround said electron beams from said substrate to said plurality of lens openings; and an adjusting coil controller operable to supply different currents to said plurality of adjusting coils.
The multi-axis electron lens may further include a non-magnetic conductive member provided between said plurality of magnetic conductive members, said non-magnetic conductive member having a plurality of through holes, wherein said through holes of said non-magnetic conductive member and said openings of said plurality of magnetic conductive members form together said plurality of lens openings.
The multi-axis electron lens may further include a coil part having: a coil provided in an area surrounding said magnetic conductive members for generating a magnetic field; and a coil magnetic conductive member provided in an area surrounding said coil.
The coil magnetic conductive member may be formed from a material having a different magnetic permeability from that of a material for said plurality of magnetic conductive members.
The electron beam exposure apparatus may further comprises at least one further multi-axis electron lens operable to reduce cross sections of said electron beams.
The electron beam exposure apparatus may further comprises an electron beam shaping unit that comprises: a first shaping member having a plurality of first shaping openings operable to shape said plurality of electron beams; a first shaping-deflecting unit operable to deflect said plurality of electron beams after passing through said first shaping member, independently of each other; and a second shaping member having a plurality of second shaping openings operable to shape said plurality of electron beams after passing through said first shaping-deflecting unit to have desired shapes.
The electron beam shaping unit may further include a second shaping-deflecting unit operable to deflect said plurality of electron beams deflected by said first shaping-deflecting unit independently of each other toward a direction substantially perpendicular to a surface of said wafer onto which said electron beams are incident, wherein said electron beam shaping unit allows said plurality of electron beams deflected by said second shaping-deflecting unit to pass through said second shaping member so as to shape said electron beams to have said desired shapes.
The second shaping member may include a plurality of shaping-member illumination areas onto which said electron beams deflected by the second shaping-deflecting unit are incident, and said second shaping member includes said second shaping openings and other openings having different sizes from sizes of said second shaping openings in said shaping-member illumination area.
The electron beam exposure apparatus may further comprise: a plurality of electron guns operable to generate said plurality of electron beams; and a further multi-axis electron lens operable to converge said generated electron beams to make said converged electron beams incident on said first shaping member, wherein said first shaping member divides said electron beams after passing through said further multi-axis electron lens.
The electron beam exposure apparatus may comprise a plurality of multi-axis electron lenses.
The electron beam exposure apparatus may further comprises: a plurality of electron guns operable to generate said plurality of electron beams; and a voltage controller, connected to said electron guns, operable to apply different voltages to said plurality of electron guns.
According to the second aspect of the present invention, a fabrication method of a semiconductor device on a wafer, comprising: performing focus adjustments for said plurality of electron beams independently of each other by a multi-axis electron lens having a plurality of lens openings for converging a plurality of electron beams independently of each other and a lens-intensity adjusting unit for adjusting a lens intensity of said multi-axis electron lens applied to said electron beams passing through said lens openings, said lens-intensity adjusting unit being provided on a substrate substantially parallel to said multi-axis electron lens; and exposing a pattern onto said wafer by illuminating said wafer with said plurality of electron beams.
The summary of the invention does not necessarily describe all necessary features of the present invention. The present invention may also be a sub-combination of the features described above. The above and other features and advantages of the present invention will become more apparent from the following description of the embodiments taken in conjunction with the accompanying drawings.